KR20110053970A - Method for producing hydroxyalkyl (meth)acrylate - Google Patents

Abstract

The manufacturing method of the (meth) acrylic-acid hydroxyalkyl ester which has a small load on a manufacturing apparatus, and is good in production efficiency. A reaction step of reacting (meth) acrylic acid with alkylene oxide while stirring a liquid containing (meth) acrylic acid and alkylene oxide in a reactor to obtain a reaction liquid containing (meth) acrylic acid hydroxyalkyl ester, And in the manufacturing method of (meth) acrylic-acid hydroxyalkyl ester which has a degassing process which vaporizes and removes unreacted alkylene oxide in a reaction liquid, stirring a reaction liquid with a stirrer after a reaction process, The stirring speed of the stirrer in the degassing process is reduced to 30 to 85% of the stirring speed of the stirrer in the reaction process.

Description

Production method of (meth) acrylic acid hydroxyalkyl ester {METHOD FOR PRODUCING HYDROXYALKYL (METH) ACRYLATE}

The present invention relates to a method for producing a (meth) acrylic acid hydroxyalkyl ester.

This application claims priority based on Japanese Patent Application No. 2008-219548 for which it applied to Japan on August 28, 2008, and uses the content here.

As a manufacturing method of (meth) acrylic-acid hydroxyalkyl ester, the method of making (meth) acrylic acid and alkylene oxide react is known. In this method, it is common to use an excess molar amount of alkyl ester than (meth) acrylic acid.

Therefore, when the reaction liquid containing (meth) acrylic-acid hydroxyalkyl ester is obtained by making (meth) acrylic acid and alkylene oxide react, unreacted alkylene oxide is contained in the said reaction liquid.

As a method for recovering the alkylene oxide in the reaction solution, the pressure in the reactor is reduced to vaporize the alkylene oxide into the gas in the reactor, the gas is introduced into the absorption tower, and the alkylene oxide contained in the gas is introduced into the absorption column (meth). The method of making it absorb in acrylic acid is proposed (for example, patent document 1).

Japanese Patent Laid-Open No. 10-330320

However, when rapidly depressurizing the inside of the reactor, the reaction solution foams, and the reactor vibrates by the foaming. Therefore, a load may be put on the manufacturing apparatus in which the reactor is installed, and there exists a possibility that a malfunction etc. may arise. On the other hand, when the pressure in the reactor is slowly reduced, foaming of the reaction liquid is unlikely to occur, but since the evaporation of the unreacted alkylene oxide takes too much time, the production efficiency is deteriorated, and the unreacted alkylene oxide is a lot of kilns ( The problem arises that it remains in (i) and the by-products, such as (meth) acrylic-acid dialkylene glycol monoester which the alkylene oxide was added to (meth) acrylic-acid hydroxyalkyl ester, generate | occur | produce. In particular, as the size of the reactor grows, problems of vibration and by-products of the reactor become remarkable.

This invention provides the manufacturing method of (meth) acrylic-acid hydroxyalkyl ester which has a low load on a manufacturing apparatus, suppresses generation | generation of a by-product, and is excellent in production efficiency.

In the method for producing a (meth) acrylic acid hydroxyalkyl ester of the present invention, while (meth) acrylic acid and alkylene oxide are reacted while stirring a liquid containing (meth) acrylic acid and alkylene oxide in a reactor with a stirrer (meth) After the reaction step of obtaining a reaction solution containing a hydroxyalkyl ester of acrylic acid and the reaction step, the reaction solution is stirred with a stirrer while depressurizing the inside of the reactor to vaporize and remove unreacted alkylene oxide in the reaction solution. A method for producing a (meth) acrylic acid hydroxyalkyl ester having a step, wherein the stirring speed of the stirrer in the degassing step is reduced to 30 to 85% of the stirring speed of the stirrer in the reaction step.

The manufacturing method of the (meth) acrylic-acid hydroxyalkyl ester of this invention has little load on a manufacturing apparatus, and its production efficiency is good. Moreover, the (meth) acrylic-acid hydroxyalkyl ester obtained by the manufacturing method of this invention has little generation | occurrence | production of reaction byproduct.

In this specification, (meth) acrylic acid means acrylic acid or methacrylic acid.

(Reaction step)

While stirring the liquid containing (meth) acrylic acid and alkylene oxide in a reactor with a stirrer, the reaction liquid containing (meth) acrylic acid hydroxyalkyl ester is obtained by making (meth) acrylic acid and alkylene oxide react.

Ethylene oxide, propylene oxide, etc. are mentioned as alkylene oxide, Ethylene oxide is preferable.

1.0-1.2 mol is preferable with respect to 1 mol of (meth) acrylic acid, and, as for the addition amount of alkylene oxide, 1.03-1.10 mol are especially preferable. When the amount of the alkylene oxide added is 1.0 mol or more, (meth) acrylic acid which is difficult to be purified tends not to be incorporated into the product, and purification by simple flash distillation tends to be possible. When the amount of alkylene oxide added is 1.2 mol or less, the amount of recovery of unreacted alkylene oxide decreases, so that the productivity is improved.

It is preferable to use a catalyst for reaction of (meth) acrylic acid and alkylene oxide. Examples of the catalyst include various amines, quaternary ammonium salts, trivalent iron compounds and cocatalysts, chromium compounds, silver or mercury, (meth) acrylic acid metal compounds, and the like. In addition, these catalysts can also be used in combination.

0.01-10 mass parts is preferable with respect to 100 mass parts of (meth) acrylic acid, and, as for the quantity of a catalyst, 0.03-3 mass parts is more preferable. When the amount of the catalyst is 0.01 parts by mass or more, the progress of the reaction tends to be faster. When the amount of the catalyst is 10 parts by mass or less, generation of by-products tends to be suppressed, which is advantageous in terms of catalyst cost.

A polymerization inhibitor can also be used for reaction of (meth) acrylic acid and alkylene oxide. Examples of the polymerization inhibitor include hydroquinone, hydroquinone monomethyl ether, catechol, phenothiazine, N, N-di-2naphthyl-p-phenylenediamine, N-oxyl compound, nitric acid, nitrate, and the like. Can be. A polymerization inhibitor may be used independently and may be used in combination of 2 or more type.

As for the quantity of a polymerization inhibitor, 0.01-1 mass part is preferable with respect to 100 mass parts of (meth) acrylic acid. When the quantity of a polymerization inhibitor is 0.01 mass part or more, there exists a tendency for a polymerization prevention effect to become favorable. When the amount of the polymerization inhibitor is 1 part by mass or less, the separation of the polymerization inhibitor tends to be good at the time of purification, and the quality of the product is good, and the cost of the polymerization inhibitor is reduced.

Reaction temperature is 50-110 degreeC normally, and 60-90 degreeC is preferable. When reaction temperature is 50 degreeC or more, there exists a tendency for reaction to progress rapidly and reaction rate improves and reaction tends to be completed. When the reaction temperature is 110 ° C. or less, the occurrence of polymerization is suppressed and the by-products are reduced.

The reaction may be carried out at any one of pressurization, atmospheric pressure, and reduced pressure. In order to make the alkylene oxide having a low boiling point exist as a liquid at the reaction temperature and to improve contact with (meth) acrylic acid, the reaction is preferably carried out in a pressure system.

It is common to introduce (meth) acrylic acid, a catalyst, and a polymerization inhibitor into a reactor, and then to introduce alkylene oxide. The addition method of an alkylene oxide can take the method of putting in batch, the method of adding continuously, and the method of adding intermittently. In the case of continuous feeding, the feeding speed may be raised or lowered in the middle. In the case where the reaction is not completed after the alkylene oxide addition, the so-called aging to maintain the reaction as it is is carried out, and the reaction is continued until (meth) acrylic acid is consumed.

The reaction has a concentration of (meth) acrylic acid in the reaction solution of not more than 1.O% by mass, in order to reduce the incorporation of (meth) acrylic acid, which is usually difficult to purify, into the product and to enable purification by simple flash distillation. Continue until it is 0.5 mass% or less.

On the other hand, the concentration 1.10% by mass of methacrylic acid in the reaction solution corresponds to 98.5% by mass in terms of the reaction rate based on methacrylic acid, and the concentration of acrylic acid in the reaction solution is 98.2% by mass in terms of reaction rate based on the acrylic acid. Becomes

Since reaction of (meth) acrylic acid and an alkylene oxide is exothermic reaction, it reacts, stirring, in order to heat-reduce and make temperature of a reaction system uniform. Moreover, there exists a tendency which can suppress the side reaction of the dropped alkylene oxide by making a reaction system uniform by stirring. What is necessary is just to determine the stirring speed in a reaction process suitably according to the capacity | capacitance and a characteristic of a kiln, the shape of a blade, and the presence or absence of a baffle plate. Industrially, reaction is performed at 10-300 rpm, Preferably it is 30-200 rpm.

The stirring speed in the reaction step is not particularly limited as long as the stirring speed in the reaction step can be effectively removed or a side reaction can be effectively suppressed, and the stirring speed can be set to a constant speed in the reaction step. You can change the number. For example, the stirring rotation speed may be changed at the time of stirring and dripping the alkylene oxide after the dropping, and the stirring rotation speed may be changed at another timing.

In the present invention, the stirring speed of the stirrer in the reaction step means a constant value when the stirring speed is constantly reacted, and the longest time in the reaction step when the stirring speed is changed in the reaction step. It means the rotation speed which was stirring.

(Degassing step)

After completion of the reaction, the reaction solution was stirred with a stirrer while the reactor was depressurized to vaporize and remove the unreacted alkylene oxide in the reaction solution.

Since the inside of a reactor is pressurized by excess alkylene oxide after completion | finish of reaction, it is preferable to gradually depressurize and to remove alkylene oxide at 10.7 kPa or less, and 2 kPa or less is more preferable.

20-110 degreeC is preferable and, as for the liquid temperature of the reaction liquid in a degassing process, 30-90 degreeC is more preferable. When liquid temperature is 20 degreeC or more, the removal rate of an alkylene oxide tends to become high. When liquid temperature is 110 degrees C or less, generation | occurrence | production of a by-product tends to be suppressed and polymerization tends to be suppressed.

In the present invention, the stirring speed of the stirrer in the degassing step is reduced to 30 to 85% of the stirring speed of the stirrer in the reaction step. By reducing the stirrer agitation speed in the degassing step to 85% or less of the stirrer agitation speed in the reaction step, even if the reactor is rapidly depressurized, the reaction liquid is less likely to foam and the vibration of the reactor tends to be suppressed. have. Moreover, when the stirrer stirring rotation speed in a degassing process is 30% or more of the stirrer stirring rotation speed in a reaction process, there exists a tendency which can suppress the dolby of a reaction liquid, and also cools reaction liquid between degassing processes. In this case, the cooling efficiency can be improved, and there is a tendency to suppress the formation of by-products due to the reaction of unreacted alkylene oxide.

It is preferable to reduce the rotation speed of the stirring immediately after the completion of the reaction, immediately before vaporizing the unreacted alkylene oxide in the reaction liquid by depressurizing the inside of the reactor.

In order to remove the unreacted alkylene oxide in the reaction solution, the pressure in the kiln is gradually lowered, but the vibration of the kiln tends to occur during high vacuum, and at this time, it is preferable to reduce the stirring speed, and to stir rotation The number may be reduced gradually.

In the present invention, the stirring speed of the stirrer in the degassing step may be once reduced to 30 to 85% of the stirring speed of the stirrer in the reaction step, and the unreacted alkylene oxide is removed in a state in which the stirring speed is reduced. The rotation speed of the stirrer may be increased after removing unreacted alkylene oxide to such an extent that vibration of the kiln is eliminated.

The removed alkylene oxide is recovered by contacting and absorbing (meth) acrylic acid by gas-liquid contact with (meth) acrylic acid, which is another raw material for the synthesis of (meth) acrylic acid hydroxyalkyl ester, in an absorption tower or the like. That is, when the target product is 2-hydroxyethyl acrylate, acrylic acid is used, and when methacrylic acid 2-hydroxyethyl, methacrylic acid is used as the absorption liquid.

An absorption tower is usually used for the catalytic absorption of the alkylene oxide. As a form of an absorption tower, multistage type | system | group, a multi-tubular type, etc. are mentioned, for example.

The temperature of (meth) acrylic acid which is an absorption liquid may be more than the freezing point in the pressure, and 20-50 degreeC is preferable. If the temperature of the absorbent liquid is 20 ° C or higher, the absorbent liquid does not solidify. When the temperature of the absorption liquid is 50 degrees C or less, the water absorption of an alkylene oxide improves.

The alkylene oxide in an absorption tower is 1 mol or less normally with respect to (meth) acrylic acid which is an absorption liquid, Preferably it is 0.005 to 0.1 mol. When the alkylene oxide is 1 mol or less, the absorbing liquid tends to sufficiently absorb the alkylene oxide, and the recovery rate of the alkylene oxide tends to improve.

(Meth) acrylic acid and alkylene oxide are suitably added to (meth) acrylic acid which absorbed the alkylene oxide obtained in this way, and it is used as a raw material of reaction which manufactures a (meth) acrylic-acid hydroxyalkyl ester. As mentioned above, 1.0-1.2 mol of alkylene oxides are preferable with respect to 1 mol of (meth) acrylic acid, and 1.03-1.10 mol are especially preferable as an input raw material ratio at this time.

In the manufacturing method of the (meth) acrylic-acid hydroxyalkyl ester of this invention demonstrated above, since the stirring speed of the stirrer in the degassing process is reduced to 30 to 85% of the stirring speed of the stirrer in the reaction process, the reactor When the inside of the reactor is depressurized to vaporize and remove unreacted alkylene oxide in the reaction solution, the reaction solution is difficult to foam even if the inside of the reactor is rapidly depressurized. As a result, the load on the manufacturing apparatus is reduced. In addition, since the pressure inside the reactor can be rapidly reduced, the production efficiency is good. The lower limit of the stirring speed of the stirrer in the degassing step is more preferably reduced to 50% or more of the stirring speed of the stirrer in the reaction step, and more preferably reduced to 60% or more. Moreover, it is preferable to reduce the upper limit of the rotation speed of the stirring in a degassing process to 80% or less of the rotation speed of the stirrer in a reaction process.

The present invention expresses the effect as the scale of the reactor increases, but it is preferable because the effect is remarkable when the reaction kiln of 1,000L to 30,000L is used.

Example

Hereinafter, an Example is posted.

EXAMPLE 1

(Reaction step)

In a high pressure reaction kiln with a stirrer, 430.45 parts by mass of methacrylic acid as a raw material, 3.44 parts by mass of iron methacrylate as a catalyst and 0.117 parts by mass of sodium nitrite as a polymerization inhibitor were added to raise the liquid temperature to 60 ° C, which is a reaction temperature. While stirring the liquid at a stirring rotation speed of 110 rpm, 255.49 parts by mass of ethylene oxide was added dropwise to the liquid over 2 hours, and after the dropping was completed, the solution containing methacrylic acid and ethylene oxide was stirred at 60 rpm while stirring at 110 rpm. Kept for 6 hours.

(Degassing step)

After completion of the reaction, the stirring speed of the stirrer was reduced to 82 rpm (75% of the stirring speed in the reaction step), and then the ethylene oxide contained in the reaction solution was stirred while stirring the reaction liquid at the stirring speed of 82 rpm with the stirrer. Vaporized. After the pressure of the reaction kiln became normal pressure, the vacuum generator was driven to suck the gas in the reaction kiln, thereby reducing the pressure in the reaction kiln and degassing the gas in the reaction kiln.

The degassing process was complete | finished when the pressure measured with the pressure gauge installed in the reaction kiln became 2 kPa, and the vacuum generator was stopped.

During the degassing process, foaming from the reaction liquid at a degree of vibrating the reaction kiln was not confirmed. Moreover, 4.17 mass% diethylene methacrylate glycol monoester was contained in obtained 2-hydroxyethyl methacrylate.

EXAMPLE 2

The methacrylic acid 2-hydroxyethyl was produced like Example 1 except having set the stirring rotation speed of the stirrer at the degassing process to 91 rpm (83% of the stirring rotation speed in the reaction process).

During the degassing process, foaming from the reaction liquid at a degree of vibrating the reaction kiln was not confirmed. Moreover, 4.13 mass% diethylene methacrylate glycol monoester was contained in obtained 2-hydroxyethyl methacrylate.

EXAMPLE 3

The methacrylic acid 2-hydroxyethyl was produced like Example 1 except having set the stirring rotation speed of the stirrer at the deaeration process to 36 rpm (33% of the stirring rotation speed in the reaction process).

During the degassing process, foaming from the reaction liquid at a degree of vibrating the reaction kiln was not confirmed. In addition, there was no case where the reaction liquid was rushing.

[Comparative Example 1]

The methacrylic acid 2-hydroxyethyl was produced like Example 1 except having set the stirring rotation speed of the stirrer at the degassing process to 110 rpm (same as the stirring rotation speed in the reaction process).

In the degassing process, foaming from the reaction liquid to the extent of vibrating the reactor was confirmed. Moreover, 4.08 mass% diethylene methacrylate glycol monoester was contained in obtained 2-hydroxyethyl methacrylate.

The production method of the present invention is useful for the preparation of (meth) acrylic acid hydroxyalkyl esters.

Claims (1)

A reaction step of reacting a (meth) acrylic acid with an alkylene oxide while stirring a liquid containing (meth) acrylic acid and an alkylene oxide in a reactor to obtain a reaction solution containing a (meth) acrylic acid hydroxyalkyl ester, And
After the reaction step, while depressing the reaction solution with a stirrer, the reactor is depressurized to vaporize and remove unreacted alkylene oxide in the reaction solution.
As a method for producing a (meth) acrylic acid hydroxyalkyl ester having
A method for producing a (meth) acrylic acid hydroxyalkyl ester, wherein the stirring speed of the stirrer in the degassing step is reduced to 30 to 85% of the stirring speed of the stirrer in the reaction step.